1. Field of the Invention
The present invention relates to a location tracking system and method, and more particularly, to a system and method for tracking the location of a person using radio frequency identification (RFID) indoors.
2. Description of the Related Art
Location tracking systems can be divided into systems for an indoor environment and systems for an outdoor environment. Location tracking in an indoor environment has various applications.
For example, the location of exhibits in a museum can be detected through a navigation application. That is, a visitor can detect information on his/her current location and the location of exhibits using map information of the museum and personalized navigation information. As another example, a network by which the locations of doctors and nurses in a hospital are shared among hospital staff to improve medical support, particularly in the event of an emergency, can be realized using location information regarding the medical staff. As yet another example, an environment in which a shopper can obtain price information, etc. at a current location in a shopping mall or a department store can be created, and thus a business model such as content manufacturing can be supported.
Location tracking systems in an indoor environment include vision-based systems using a camera and sensor-based systems using an infrared sensor. However, vision-based systems are disadvantageous because they raise privacy concerns and require heavy computation. Accordingly, sensor-based location tracking systems are the focus of ongoing study.
One conventional sensor-based location tracking system is called a Cricket (Nissanka et. al, The Cricket Location-Support System, 6th ACM International Conference on Mobile Computing and Networking, 2000). The Cricket tracks the location of a user using a RF sensor and an ultrasonic sensor. That is, a transmitter simultaneously transmits a RF signal and an ultrasonic signal, and a receiver receives the two signals. The receiver measures the propagation delay times of the two signals, and uses the difference in the propagation delay times and the difference in the velocities of the two signals in the atmosphere to calculate the distance between the transmitter and the receiver. Using the calculated distance, it can be determined which transmitters are in close proximity to the receiver. The location or coordinates of the receiver in two-dimensional space can be obtained by triangulation using three transmitters in close proximity to the receiver.
However, systems such as the Cricket are expensive to implement. Accordingly, a simpler and more economical system and method of location tracking are required.